In prior art digital detection systems for phase shift keyed signals, recovery of the carrier signal is essential for operation. For example, in U.S. Pat. No. 3,993,956, a Costas loop is used to recover the carrier signal and control the detection circuits. Until carrier synchronization is obtained in the Costas loop, the demodulation of data cannot take place. In addition, the data is demodulated a full bit at a time. None of the prior art systems provide for immediate and continuous demodulation of the received DPSK signals.